Source contributions of surface ozone in China using an adjoint sensitivity analysis.

Area of Science:

• Environmental Science
• Atmospheric Chemistry
• Public Health

Background:

• Air pollution, particularly ozone (O3), poses a significant threat to public health in China.
• Understanding the complex source-receptor relationships of O3 pollution is crucial for effective mitigation strategies.

Purpose of the Study:

• To quantitatively assess source-receptor relationships for surface ozone (O3) across China.
• To differentiate the contributions of local versus transboundary emissions to O3 pollution in various Chinese regions.

Main Methods:

• Application of the Community Multiscale Air Quality (CMAQ) adjoint model.
• Quantitative assessment of precursor emissions (NOx and VOCs) and their impact on O3 concentrations.
• Defined five receptor regions: Northern China (NC), Southern China (SC), Pearl River Delta (PRD), Yangtze River Delta (YRD), and Beijing-Tianjin-Hebei (BTH).

Main Results:

• Atmospheric processes like advection can counteract O3 removal in VOC-limited areas.
• Transboundary transport significantly contributes to O3 pollution in SC, NC, and YRD.
• PRD and BTH O3 pollution are predominantly influenced by local emissions.

Conclusions:

• Local emissions are the primary drivers of O3 pollution in PRD and BTH.
• Anhui, Hubei, and Jiangsu are major NOx and VOC sources for SC and YRD.
• Beijing and Tianjin significantly contribute to O3 in NC and BTH.